This invention relates to a damming device intended for forming a liquid-damming protective bank, which comprises components with the purpose of holding the device anchored against a surface, more precisely by friction action as a consequence of a vertically directed hydraulic pressure urging the device against the surface, as well as counteracting that liquid streams from a wet side or flood side to a dry side, means being provided between the surface and the actively acting protective bank for the purpose of draining away flood liquid which possibly leaks in under the device from the flood side so as to hold the surface on the bottom side of the device extending from the edge of the draining means being closest to the flood side to the dry the side at or close to atmospheric pressure with the purpose of achieving a maximum pressure difference in relation to the hydraulic pressure holding the device urged against the surface.
A damming device of the kind generally described above is previously known by SE 9500795-1. More precisely, this patent discloses a mobile device, the liquid-damming component of which is constituted by a flexible casing that may be expanded by being filled with water or air. An advantage of this device is that it may be stored in a collapsed state in which it occupies a minimum of space in conjunction with storing and transportation, and thereafter it may be expanded on location in a fast and simple way in areas where there is a risk for a flood. Furthermore, the device is easily and flexibly pliable, which means that the device may advantageously be used in order to dam water on soft and uneven surfaces, which may have inferior bearing capacity. In practice, the device also includes a relatively wide skirt connected to the flood side of the casing, which skirt forms the anchoring component of the device. By the fact that this skirt is wide, a reliable anchoring of the device is obtained. However, depending on the field of use, the known damming device is also associated with certain disadvantages. Thus, a disadvantage is that the flexible casing, made of plastic or rubber, runs the risk of being punctured at careless handling. Another disadvantage is that the casing occupies a considerable width besides the skirt. In case the casing would be given a large height with purpose of counteracting floods having high water lines, the total width of the device would be considerable. For this reason the applicability of the device is in practice limited to relatively low water levels, for instance within the range of 0,5-1,5 m. At higher water levels, the device would require too large a total width in order to be able to be used successfully for instance inside densely built-up areas, in particular built-up areas with narrow streets.
In addition to the above-mentioned damming device, also mechanical constructions of many different embodiments (see for instance U.S. Pat. Nos. 898,984, 4,136,995, 4,692,060, 4,921,373 and 5,470,177) are used for flood control purposes. These previously known mechanical flood control devices are based on the fact that the power that the water or liquid pressure exert on them should, by support legs or other mechanical elements, be linked to the ground. However, this implies that the ground has a good bearing capacity. This is something which far from always is the case in the practical flood situation. Theoretically, the mechanical damming devices may be erected to a high height, but this requires that the ground is strong and that the constructions are dimensioned very solidly. It can generally be said that the known, mechanical damming devices, at least theoretically, have a larger damming ability than the device known through SEE 9500795-1 that works with a flexibly, expandable casing. On the other hand, the last-mentioned device has a more reliable anchoring ability than the mechanical damming devices.
The present invention aims at obviating the above-mentioned disadvantages and shortcomings of the above-related main categories of damming devices and at creating an improved damming device. Thus, a primary object of the invention is to create a damming device that, for a given total width, is capable of controlling high water levels. A further object is to create a device which does not run the risk of being punctured and thereby collapse in an active state. Still another object is to create a damming device which is robust in its active, liquid damming state, as well as constructionally simple and thereby cheap to manufacture. The device should furthermore be simple to transport and handle in conjunction with the erection of a protective bank.
According to the invention, at least the primary object is attained by the features defined in the characterizing clause of claim 1. Preferred embodiments of the invention are furthermore defined in the dependent claims.